The present invention relates to an image-receiving sheet used to transfer and record a visual image formed by developing an electrostatic latent image by using a toner, and, especially, to a highly transparent OHP image-receiving sheet used for copying machines and printers using an electrophotographic system in which the mechanical carriage quality is greatly influenced by the surface smoothness of an image-receiving sheet.
In recent years, methods of forming a full color image by using an electrophotographic system has been put to practical use wherein toners respectively having three colors consisting of a yellow color, magenta color and cyan color or four colors including a black color in addition to these three colors are used.
An image-receiving sheet used in this electrophotographic system has a general structure, in which a receptor layer for recording an image is formed on a substrate, to record and store recording information including characters and images without fail. This image-receiving sheet is used for OHPs (overhead projectors) as information-conveying means utilized in, for example, lectures, schools, business offices and other explanatory meetings and exhibitions.
While, in current full color copying machines and printers using an electrophotographic system, a toner offset and further a receptor layer offset in the case of OHP sheets provided with a receptor layer for recording an image tend to be produced on account of heat and pressure when a toner is melted and fixed in a step of fixing the toner. Therefore, in such a system, silicon oil is usually applied to a fixing roller in the fixing step.
In current full color copying machines and printers using an electrophotographic system as mentioned above, an image-receiving sheet is supplied from a cassette or by hand. In this case, the front end portion of the image-receiving sheet is caught up in a roller for carriage, giving rise to the problem of the degree of catching force. Also, there is the drawback that the image-receiving sheet approaches a fixing roller with difficulty.
In, especially, image-receiving sheets for OHP, the surface thereof is not so much roughened by designing the haze (misting value) to be 10% or less and preferably 5% or less to maintain the transparency with the smoothness being about 1000 to 5000 seconds.
Such an image-receiving sheet tends to pose the problem of carriage inferior in printers.
As stated above, there are no image-receiving sheets which are conventionally used in an electrophotographic system and excel in toner-fixing ability and in the qualities needed in carriages inclusive of paper-feed in a well-balanced manner in electrophotographic copying machines and printers. Particularly, there is no image-receiving sheet suitable to a full color system in which toners are overlaid and fixed.
In light of this situation, it is an object of the present invention to provide an image-receiving sheet which has better toner-fixing ability and gives high image quality and high carriage qualities needed in electrophotographic copying machines and in printers.
The above object can be attained by the provision of an image-receiving sheet according to the present invention, the image-receiving sheet comprising a layer containing a binder and a filler on at least one surface of a substrate, wherein the containment layer has a Beck smoothness of 2000 seconds or less and the haze of the image-receiving sheet is 5 to 15%. The invention serves to stabilize carriage qualities in printers and the like.
Preferably the image-receiving sheet is provided with a layer having a Beck smoothness of 20000 seconds or less on the surface opposite to the surface of the substrate on which the containment layer is formed. The invention reduces the contact points between image-receiving sheets and stabilizes the carriage qualities.
Preferably the containment layer is either one of a receptor layer for recording an image and a backface layer.
It is preferable to control the resistance of the image-receiving sheet of the present invention according to the following methods.
A resistance control layer is formed on the outermost layer of the image-receiving surface and/or backface of the image-receiving sheet.
Preferably a resistance control layer is formed between the containment layer and the substrate and/or between the layer having a Beck smoothness of 20000 seconds or less and the substrate.
Given as examples of resistance control materials used for the resistance control layer are ion-conductive materials, fine metal particles and conductive polymers having conjugated double bond of xcfx80 electrons.
Preferably the image-receiving sheet has a parallel ray transmittance of 70% or more.
The action of the present invention is as follows.
In an image-receiving sheet provided with a layer containing a binder and a filler on at least one surface of a substrate, the containment layer has a Beck smoothness of 2000 seconds or less and the haze of the image-receiving sheet is designed to be 5 to 15%. This structure stabilizes the carriage qualities in printers or the like and gives a high quality to an image of an OHP projector.
The above containment layer is either one of a receptor layer for recording an image and a backface layer. Also, in the image-receiving sheet, a layer having a Beck smoothness of 20000 seconds or less is provided on the surface opposite to the surface of the substrate on which the containment layer is formed, further improving the carriage qualities.
Further, a resistance control layer is formed on the outermost layer of the image-receiving surface and/or backface or between the containment layer and the substrate and/or between the backface layer and the substrate. This is the reason why good antistatic ability and toner-fixing ability can be maintained. The use of ion-conductive materials, fine metal particles and conductive polymers having conjugated double bond of xcfx80 electrons as the resistance control materials for the resistance control layer has the advantage that the coating surface is not sticky and there is no phenomenon that the resistance material is transferred to the contact surface during storing to thereby change the surface resistivity.